MAPK1 and RASopathy: These phenotypically overlapping syndromes are collectively referred to as RASopathies, owing to the fact that they all share germline gain-of-function mutations in genes encoding components of the RAS-RAF-MEK-ERK pathway (Aoki et al., 2008; Simanshu et al., 2017; Bustelo et al., 2018; Dard et al., 2018).